|Microarrays reveal patterns of Y chromosome variation|
Sarah E. DeWeerdt
April 9, 2001
The Y chromosome, passed down through generations from father to son, has long tantalized researchers, who thought it might yield insight into the history and migration of human populations. But at first, the Y chromosome seemed to lack enough variation to provide that information; then, as more variations were discovered, large-scale studies seemed impractical without a quicker method of sequencing and analyzing the variations. Now, a team of Finnish and Swedish researchers has employed microarrays to analyze a large number of Y chromosome variations simultaneously and rapidly, and has been able to glean information about the history of certain population groups suggesting that Finland experienced two waves of migration.
The research team, led by Mirja Raitio, of the National Public Health Institute in Helsinki, Finland, analyzed 25 previously known single-nucleotide polymorphisms, or SNPs, on the Y chromosomes of men from various Finno-Ugric-speaking populations. The Finno-Ugric languages, including Finnish, Estonian, and Hungarian, are unrelated to the Indo-European languages spoken in most of Europe.
All 300 people in the study, published in the March 2001 issue of Genome Research, had the same DNA sequence for 19 of the SNPs. Six of the SNPs were polymorphic, and these variations came in 6 different combinations, or haplotypes, on the Y chromosome. Each population had a distinctive profile of haplotypesfor example, 55 percent of people in the Ob River group had the H26 haplotype, which was absent from other groups in the study. Still, like many researchers who have studied human genetic variation in the past, the team found that there was more variation within the groups than among them.
The groups in the present study included Finns from various regions of Finland; Karelians from western Russia; speakers of Mansi and Khantyi from the Ob River region in western Siberia; and three groups of Saami, or Laplanders, descendants of nomadic reindeer herders who live in the northern regions of Scandinavia and Russia's Kola Peninsula.
Among the Finns haplotypes H2 and H16 were especially common. H2 is considered an 'ancestral' haplotype, and H16 probably arose from it by two mutations. At one point a certain C on the Y chromosome became a G; later, a certain T became a C. According to the authors, the presence of both H2 and H16 among Finns, as well as variations in the frequency of haplotypes between people from different regions of Finland, supports archaeological evidence that Finland was settled in at least 2 waves of migration.
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